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Thread: Crank Question

  1. #1
    Rocket Hips
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    Crank Question

    I'm replacing the crank on my old Trek. Will any double with a square taper fit on the BB?

  2. #2
    Senior Member demoncyclist's Avatar
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    Theoretically, you need to make sure that the new crankset sits exactly like the old one to work correctly. If this was my bike, I would replace both the crankset (including rings if they haven't been replaced in a long time) and the BB. That way you get a perfect match. In addition, the chain and cassette are probably worn too. Why are you replacing the cranks???
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    Rocket Hips
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    Well it's a fixie and I'm putting some 165mm cranks on there to replace the 170's.

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    Senior Member sydney's Avatar
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    Quote Originally Posted by OrangeJTM46
    Well it's a fixie and I'm putting some 165mm cranks on there to replace the 170's.
    Well, that does not matter. Taper on the spindle has to match the crank and different cranks have different spindle length requirements. Physically, it can be crammed on, assuming the ring doesn't end up hitting the chainstay,but the chailnime could be badly whacked.

  5. #5
    I couldn't car less. jeff williams's Avatar
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    Maybe..same amount of rings? Yes I think..do a measure and try it.
    The chainline on geared bikes can be altered some...more than a ss or fixed gear bike.
    the tensioner will let the chain angle ok.

  6. #6
    Te mortuo heres tibi sim? scrublover's Avatar
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    the answer is yes.

    BUT

    it may really throw your chainline out of whack. or it may not at all. if it does only a little, you can move your bb with some spacers. or you cans space your chainring out a bit. or you can space your fixed cog out a bit. or a shorter/longer spindle BB if needed. instances like this, where chainline may be off by only a tiny bit, are where adjustable chainline BBs come in handy.

    what is the old crank? try and find as similar to that as you can, even if you only have "eyeball" measurement to go on.
    Last edited by scrublover; 02-23-05 at 04:30 AM. Reason: ooops reply meant for original poster.
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